1. Field of the Invention
The invention relates to a thermoplastic resin composition, a thermoplastic resin product molded from the composition and an outside plate part for a vehicle using the thermoplastic resin molded product.
2. Description of the Related Art
Conventionally, consideration has been given to an idea that even outside plate parts including outer panels of a vehicle such as a fender panel and a hood are made of a resin in a series of efforts to achieve more of the light weight in a vehicle such as an automobile and in some of vehicles, resin (resin-made) outside plate parts have been actually used in practical aspects.
In a case where a so-called on-line coating is performed, in which coating on the whole of the body is performed in a coating line in a state of the body into which the outside plate parts of a vehicle such as a fender panel and a hood made from a resin are assembled, a problem has arisen that thermal deformation in the resin outside plate parts occurs with ease by heating in a drying furnace after the coating.
Hence, it has been thought that outside plate parts of a vehicle is molded using a thermoplastic polyamide resin (for example, nylon resin) as a base material, which is a resin material high in heat resistance, that is a resin material comparatively low in thermal deformation caused by heating. On the other hand, since outside plate parts of a vehicle requires impact resistance more than a given level thereof, an elastomer component such as a rubber component high in impact absorption is generally added in order to meet such a requirement (for example, see Japanese Patent Laid-open Publication No. 07-316423 (corresponding to U.S. Pat. No. 5,874,176) and No. 11-335553). Also, a method is known, in which an elastomer component high in impact absorption is added, and further a filler component is mixed in order to meet the requirement (for example, see Japanese Patent Laid-open Publication No. 07-316423, No. 11-335553 and No. 08-302025).
However, in a case where a polyamide resin is used as a base material to which an elastomer component is added, if one of the both components has, for example as shown in FIG. 15, good characteristics in regard to impact resistance and heat resistance, a characteristic of the other component is lowered, that is there is a so-called a trade-off between the characteristics. That is, if, for example, a mixing quantity of a rubber component (m-EBR) is larger to thereby increase impact resistance, that is if a low temperature IZOD value is larger (see a kinked solid line of FIG. 15), heat resistance decreases while a thermal deformation quantity increases (see the broken kinked line of FIG. 15), and in a case where heat resistance is better and a thermal deformation quantity is less, impact resistance is lower. Therefore, it is a reality that both characteristics are quite difficult being compatible with each other satisfactorily.
In a case where an elastomer component is added and a filler is mixed as well, a polyamide resin in which the filler is mixed is excellent in heat resistance, while on the other hand, a polyamide in which an elastomer component is mixed is excellent in impact resistance, but since heat resistance and impact resistance are in a relationship of a so-called trade-off as described above, it has made difficult being compatible between heat resistance and impact resistance only if both additives are simply mixed into the resin. That is, no composition has been available in which heat resistance and impact resistance are truly compatible with each other by mixing an elastomer component and a filler therein.
Note that outside plate parts of the body such as a fender panel and a hood in the state of an assembled body are, as described above, subjected to coating generally on the whole of the vehicle with a melamine-based paint in on-line coating, followed by heating and drying the body at a baking temperature of the order of about 140° C. in a drying furnace, wherein it is important to outside plate parts made from a resin that a good paint adherence is achieved on surfaces of the outside plate parts (coat adherence) in the series of coating.